In a typical ink-jet printing system, ink droplets are ejected from a nozzle at high speed towards a recording medium (e.g., film) to produce an image on the recording medium. An image processing system can convert pixel values of an image into an ink output value for a printer. The ink output values comprise the raw values used by the printer as a command corresponding to the quantity of ink droplets to eject at a given point on the recording medium. Ideally, the printer will output a quantity of ink in the area on the recording medium corresponding to the pixel such that that area appears to an observer to have the color, tone, tint, shade, and optical density of the pixel in the image.
A given pixel value can correspond to multiple ink output values. For example, a pixel of a given color, tone, tint, shade, and optical density can be reproduced by the printer using a combination of multiple colors of ink. A typical ink-jet printer uses black, cyan, magenta, and yellow, although other and/or additional colors can be used. Accordingly, to reproduce a given pixel, the printer can output some portion of one or more of the ink colors available.
A transfer function can be used by the image processing system to convert the pixel value to the corresponding ink output values for each ink nozzle (e.g., each different color) on the printer. In some examples, the transfer function can take the form of a look up table (LUT) relating pixel values to the ink output values.